U.S. Pat. Nos. 9,072,384 and 9,392,872 disclose a chair that allows small, subtle multi-directional motion by the user while maintaining the functionality and space requirements of a stack chair. The multi-directional motion is facilitated by flexible supports mounted to the frame of the chair which suspend and support the chair's seat. A range of motion in the seat is thereby provided which is limited by an integrated stopping mechanism built into the chair's frame. Allowing the user to change seating attitude with concomitant motion of the chair seat improves user comfort and prevents or delays user fatigue during long seating sessions while maximizing efficiency of work accomplished during a seating session.
U.S. Pat. No. 9,010,867 discloses an article of furniture comprising a stool configured to be used on a generally horizontal surface such as a floor. The stool comprises a seat and a base comprising a rounded bottom surface configured to rest upon the floor. A mass is positioned beneath the seat so that the base is at equilibrium in a first tilted orientation relative to the floor. The base can be tilted to second tilted orientation relative to the floor by tilting the rounded bottom surface of the base relative to the floor.
U.S. Pat. No. 8,998,319 discloses a seating device including a seat, a post positioned below and attached to the seat, a base positioned below and attached to the post, an inflatable bladder positioned below and attached to the base, and a guard positioned below and attached to the base. The inflatable bladder comprises a portion of a sphere, the portion comprising less than 35 percent of the sphere. The inflatable bladder covers over 35 percent of an underside of the base, and the guard comprises a solid circular piece extending downward from the base with a bottom edge located above a bottom of the inflatable bladder when the inflatable bladder is fully inflated.
U.S. Pat. No. 8,764,116 discloses an item of seating furniture containing a seat providing a seat surface, a generally circular foot panel positioning the item of seating furniture on a floor, and a central part, which connects the seat to the foot panel and of which a vertical center axis runs centrally through the foot panel. The foot panel is of at least partially convex configuration and that side of the foot panel which is directed toward the floor is configured, at least in part, as a non-slip surface. This creates an ergonomic item of seating furniture which stands in a stable state.
U.S. Pat. No. 7,478,878 discloses a self-righting chair having: (i) a seat; (ii) a base member; and (iii) a connector connecting the base member to the seat, wherein the base member has a curved configuration, and wherein the base member has sufficient weight, such that when a force is exerted to move the chair from a substantially vertical position to a tilted position, the chair is moved from the substantially vertical position to the tilted position, then returns to the substantially vertical position when the tilting force is removed.
U.S. Pat. No. 6,834,916 discloses a gardening stool that allows for tilting and pivoting. The gardening stool has an elongated base connected to a seat by a post. The elongated base is convex and is tapered towards the front for pivoting. The base may include a flattened region located toward the rear of the post for stability. The base may further include compartments for holding tools.
U.S. Pat. No. 3,558,186 discloses a child's high chair consisting of a plurality of hollow cylinders of successively smaller diameter, a chair, and a feeding tray. The cylinders being adapted to be stacked, one upon the other, and secured together, to form a high base for the chair and the feeding tray mounted thereon. When disassembled, the several components being nestable, one within the other, to form a compact carrying package of which the feeding tray forms the cover.
U.S. Pat. No. 2,560,785 discloses a hassock or the like comprising a plurality of separate structural units assembled in a plurality of side-by-side stacks, a pair of cover members extending across opposite ends of the stacks, and tie members fastened to the cover members and extending through the units in the stacks, whereby the units are held together by the tie members and cover members to form a unitary frame.
European Patent No. EP 1334675 discloses a stool having a base provided with a convex lower surface and a soft skirting, a central column which can be fitted with a height adjusting mechanism, and a seat facilitating a squatting position. The outer contours of the seat are curved, resulting in three sections shaped like a bicycle seat, allowing the child to sit in a stable position with the knees slightly apart and the pubic bone supported by the projecting section. The stool can be tilted because of the convex center of the base and the surrounding soft skirting which also protects the child from injury when his/her fingers get caught under the base.
Japanese Patent No. JP 10-229952 discloses a bath stool having of a top seating part, the lowest leg part, and a plurality of mutually stackable sections arranged in-between. The number of sections to use is determined depending on child's height when sitting, with the stool height adjusted by stacking the seating part, leg part and in-between sections like picnic boxes. Thus, when a parent and a child take a bath together, the child can sit on the stool with the head above the water level in the bathtub, thereby enabling them to enjoy taking a bath stably and leisurely.